1. Field of the Invention
This invention relates to a diaphragm field, particularly to an acoustic metal diaphragm which solves the problem of the high frequency and maintains the good quality of the sound.
2. Description of the Related Art
Generally, a sounding unit is a main component impinging on the sound quality of an earphone, and a diaphragm is a critical part for the sounding unit. The diaphragm is one of the important components in various acoustic devices, such as earplugs, earphones and microphones. There is a wide variety of diaphragms, such as paper diaphragms, plastic diaphragms, metallic diaphragms and synthetic fiber diaphragms. The conventional diaphragm is usually a single diaphragm shaped by one kind of material. The high frequency and the low frequency are usually created when the acoustic device make sounds. To solve the problem of the high frequency of the acoustic device, the conventional way is to print on the diaphragm, which increases the rigidity of the diaphragm. However, this way cannot ensure that the diaphragm gets softness and rigidity at the same time, with the result that the frequency response of the acoustic device cannot be wide enough and the sound quality or timbre thereof cannot be good enough. FIGS. 1-3 are respective graphs showing the curves of frequency response and noise (rub & buzz) for a big earphone, a microphone and a small earphone. From the graphs, the value of the sound pressure goes down straight and the bandwidth attenuates very fast when the sound frequency is above 10 KHZ, which causes a large decrease in the effect of the sound quality. Especially, shrill sounds may occur in the small earphone.